The present invention relates generally to active matrix displays, and more particularly to active matrix displays having nonlinear elements in pixel elements.
FIG. 1 shows a section of a conventional active matrix display. The conventional active matrix display in FIG. 1 includes a matrix of pixel elements (e.g., 50AA-50LA, 50AB-50LB, and 50AC-50LC), an array of column conducting lines (e.g., 30A, 30B, and 30C), and an array of row conducting lines (e.g., 40A-40L) crossing the array of column conducting lines. A row conducting line (e.g., 40A) is electrically coupled to one row of pixel element (e.g., 50AA-50AC). A pixel element (e.g., 50AB) includes a switching transistor 52 having a gate electrically connected to a row conducting line (e.g., 40A) and a capacitive element 54 having a terminal electrically connected to a column conducting line (e.g., 30B) through a semiconductor channel of the switching transistor 52.
In operation, during a predetermined time period, a row of pixel elements (e.g., 50AA-50AC) is selected for charging by applying a selection signal on a row conducting line (e.g., 40A). During the next predetermined time period, next row of pixel elements (e.g., 50BA-50BC) is selected for charging by applying a selection signal on the next row conducting line (e.g., 40B).
When charging a row of pixel elements (e.g., 50AA-50AC), each pixel element is charged with a data signal on a column conducting line. For example, the pixel elements 50AA, 50AB, and 50AC are charged respectively with the column conducting lines 30A, 30B, and 30C. When charging the next row of pixel elements (e.g., 50BA-50BC), each pixel element in this next row is also charged with a data signal on a column conducting line. For example, the pixel elements 50BA, 50BB, and 50BC are charged respectively with the column conducting lines 30A, 30B, and 30C.
During the predetermined time period for charging a row of pixel elements, the switching transistors in the pixel elements needs to be fast enough to change their conducting states. A switching transistor may need to change from the non-conducting state to the conducting state or change from the conducting state to the non-conducting state. When an active matrix display has a total of N rows, if the time period for charging all N rows of pixel elements progressively is a frame time period T0, the allocated predetermined time period for charging one row of pixel elements can be less than T0/N. For high resolution displays in which N is quite large (e.g, N is larger or equal to 512), the allocated predetermined time period can become quite short such that it put on stringent demand on the switching speed of the switching transistors. For lowering the manufacturing cost, it is desirable to reduce the switching speed requirement for the switching transistors by finding new forms of active matrix displays and by finding new method for driving these active matrix displays. Also, it is desirable to improve the display quality of those active matrix displays that use nonlinear elements, such as thin film diodes (TFD) or metal-insulator-metal diodes, as the switching elements for pixel elements.